On the Energy Nonconservation in the FET’s Equivalent Circuit Capacitance Model

This article answers the long existing quest on how to conciliate a non-reciprocal capacitance formulation in the equivalent circuit model of field-effect transistors (FETs) with the energy conservation principle. The nonreciprocity of the
${C}{(}{v}{)}$
matrix, observed from both simulations and measurements, is shown not to be the consequence of an energy non-conservative capacitive system, but rather a collateral effect from describing the FET through the standard
$\pi $
equivalent circuit that fits the measured Y-parameters. In this work we demonstrate how the conductive and capacitive elements used to represent the FET’s channel at a local spatial point are then externally mixed together due to the Y-parameters formulation. The extracted nonlinear capacitances from the FET’s equivalent circuit model are therefore not actual capacitive elements that should abide to the energy conservation principle.